U.S. Pat. No. 6,344,405 discloses a semiconductor device that comprises, a source, an oxide-supported gate and a drain, which extend lengthwise along a substrate. The device requires a threshold voltage Vt to turn on the device, from a nonconductive, off state. Leakage currents near the source and drain tend to occur within a source depletion region and a drain depletion region. These depletion regions are in the substrate beneath the oxide-supported gate, and between the source and the drain. The source and drain depletion regions electrically couple to the transistor source and the transistor drain, respectively, which contributes to leakage current.
When the length of the gate, Lgate, is made desirably smaller, for example, when Lgate decreases below 0.1 μm (micrometers), these depletion areas have a tendency for electrically coupling to each other, which increases the likelihood of a leakage current between the source and the drain. Such an electrical coupling, as Lgate decreases, is referred to as, a short channel effect (SCE), or alternatively as, a punch through effect.